How Austin’s Biggest Agency Threw One of the Best Parties at SXSW [Video]

Best known lately for Petsmart's perfectly bizarre spot and an irreverent Avocados from Mexico Super Bowl ad, GSD&M is one of the more versatile agencies in the industry. And being located in Downtown Austin gives them a unique perspective on South by Southwest—and of course, a canvas on which to paint one of the festival's biggest shows each year.

The event's poster promoted a "Super Secret Headliner."

In our video above, we sat with chief creative officer Jay Russell and group creative director Bill Bayne to hear exactly how they put on a party of this scale (there were an estimated 3,500 people in attendance on Monday night).

The agency's massive campus healthily accommodated the crowd, serving up free food and drinks from various local sponsors as well as three of GSD&M's clients—Popeyes Louisiana Kitchen (which debuted its new Red Stick Chicken menu item), Pacifico and Southwest Airlines (which held a photo contest, with the winners getting to watch the night's concert in airline seats in the front row). There were also vendors and pop-up art installations to browse.

But the real draw was the music—an acoustic set by Matt Vasquez of Delta Spirit, Coyotes, Kate Tempest and Houndmouth.

The party closed with a "Super Secret Headliner"—so secret, in fact, that we were asked to turn off our cameras. It turned out to be Austin native, Grammy award winner, and soul and blues guitarist Gary Clark Jr.—who melted faces with his fuzz-box-wah-pedal rock 'n' roll mastery.

How much does an act like Gary Clark Jr. cost a marketing shop to book? A source at another major agency hinted that he's fetched six-figure paychecks for recent company-sponsored events. That's a pretty penny for the increasingly mainstream artist, who's played along side the likes of Beyoncé and Foo Fighters.

Take a look at the video above, and check out some of the sights and sounds of the night. And as a bonus, below are some Instagram videos of Clark's performance from partygoers in attendance.